1. Field of the Invention
This invention relates to an improvement of a toner dispensing apparatus for receiving toner from a toner container unit prepared separately in an electrostatic reproducing apparatus which uses a dry developer.
2. Description of the Prior Art
In an electrostatic reproducing apparatus using a dry two-component developer or one-component toner, toner is consumed in the process of reproduction and it becomes required to resupply toner after many copies have been reproduced. Resupply of toner is made usually by filling up toner into a toner hopper of the electrostatic reproducing apparatus from a toner container unit which houses therein toner. Toner is in the form of powder which has an average particle size of several tens microns, and hence is liable to scatter. Therefore, when toner is resupplied with the toner container unit being mounted to a toner inlet opening of the hopper, it happens very often that toner escapes or scatters to the outside and this causes contamination in the surroundings. It has been also experienced oftenly that there occurs toner contamination due to possible erroneous operation at the time of mounting the toner container unit or during other necessary operations.
From this reason, there has been proposed such a construction that a toner container unit closed by a cover is mounted on a toner hopper closed by a cover, and then the slide cover of the toner container unit and the openable cover of the toner hopper are opened at the same time. However, when both the slide cover and the openable cover are opened at the same time, toner starts to drop upon opening of the slide cover, so that the upper surface of the leading end portion of the openable cover is contaminated with toner each time. It was thus unavoidable that the opening portion of the toner hopper is subject to toner contamination, at the time when the toner container unit is removed after resupply of toner.
Further, if the toner container unit should be removed erroneously during resupply of toner, toner may scatter into the surroundings of the apparatus, thereby resulting in the uncontrollable state oftentimes.
In addition, the toner hopper has encountered the following problem to be solved. Since the hopper resupplied with toner from the toner container unit has to feed toner uniformly all over the width of recording paper, it has a length corresponding to the width of recording paper in usual cases. On the other hand, the opening portion of the toner container unit has a relatively small length, so that toner is filled into the hopper one-sidedly, if the toner container unit is mounted on the hopper and then opened to allow the toner just to drop from the toner container unit into the hopper. Development in this state may results in such a disadvantage that the toner is not agitated sufficiently in the development section and there occur variations in darkness of the copy in the widthwise direction, whereby the desired uniform development is not secured.
Further, in case toner in the toner container unit has been solidified due to moisture or so, the toner will remain in the toner container unit and will not drop into the hopper, even when the slide cover of the toner container unit and the openable cover of the hopper are opened together. In this case, therefore, resupply of toner is not attained to the desirous extent very oftenly.
Moreover, in a toner hopper having a cover which is slidable to be opened and closed, toner tends to adhere on the sliding surface and the cover suffers greater resistance in its sliding movement. And it becomes difficult to open and close the cover in not a few cases.